1. Field of Use
The disclosure illustrates a novel method and apparatus to line pipes containing tortuous elbows and bends.
2. Description of Related Art
Prior art demonstrates numerous methods to line pipelines, conduits and passageways with an in situ pipe line spray apparatus in order to restore asset integrity. Though several of the prior art submissions suggest viability in straight line pipe geometries it is our intent to demonstrate that the prior art methods and apparatus' cannot effectively produce a consistent lining or membrane in pipelines and conduits containing standard pipe fitting bends whereas the present invention can.
Throughout the US and much of the world, most pipelines and conduits are built to standards that dictate internal pipe dimensions, wall thickness, connection geometries and bend radii among other specifications. A typical pipeline comprises a majority of straight pipe lengths but also contains a number of direction changes constructed of standard pipe fittings. 45° and 90° elbows are common. For example, a typical bend radius for a standard wall 8 inch pipe is 12 inches. This is a tortuous bend for a pipe lining robot with all of its mechanical devices to traverse.
In Davis, U.S. Pat. No. 6,986,813, the patent teaches a sprayed in place pipe lining apparatus and method thereof. While this may be a feasible operation for short length, large diameter straight pipe, the equipment of the prior art, due to its overall length, cannot be inserted or retracted from an underground pipe with the access being a manhole or vault with a diameter or horizontal dimension of less than 5 feet. Neither can the device negotiate even a simple 45° bend in a line. There are also limitations in diameter where the smallest viable pipe size is greater than 6 inches.
Some prior art lining devices can traverse 90 degree bends provided that the lining device's overall length is not more than 2″ greater than the pipe I.D. This is a severe restriction. Also that even though the lining device can traverse the 90° bend, it would not be able to spray consistent liner thickness as the dissipation device would be in immediate proximity to the outside radius of the pipe wall. Not only would there be extremely heavy build-up on this area of the bend but more than likely there would be minimal and most likely no lining material on the inside radius of the bend. More importantly the lining device may have a catastrophic failure due to lining material velocity and the subsequent rebound of the lining material back onto the dissipation device due to its close proximity and angle of trajectory. The apparatus of the present disclosure avoids these limitations.
Weisenberg, U.S. Pat. No. 7,591,901 improves on these shortcoming by streamlining the profile of the stated apparatus and adding articulation junctures between the housings and the reciprocation head to help the device navigate slight offsets and protrusions in a pipeline. Review of the description and drawings demonstrate it would be impossible to be short enough or narrow enough to navigate a typical pipe bend in a pipe of less than 30 inches in radius while maintaining concentricity of the dissipation device. Diameter restrictions again apply here where the stated limitation is 5.5 inches.
It is therefore desirable to present an invention that can apply a uniform structural membrane in pipelines and conduits that can readily navigate typical pipe size fittings and bends in diameters down to 4 inches. The accompanying specification, through the disclosure, drawings and claims, will teach a method and apparatus to accommodate these needs.